Collisions

[Correale, Ernest]

I should have been more specific.  My intent was only to suggest to Steve
that some collisions are normal and not a significant cause for alarm. If
the situation is causing network slowdowns, then he may need to begin a more
serious investigation of the problem.

Client ACKs are a product of the 802.3 Ethernet protocol spec and are
implemented in the protocol stack.  In Ethernet communication, the client
will send an acknowledgement (ACK) for each window of data received.  This
is how the server knows whether or not to retransmit data due to an error or
loss.  As session time increases the transmission window should lengthen to
an appropriate degree, reducing the number of ACKs and the subsequent
collision rate.   

You are absolutely correct in saying physical layer issues can and often do
cause an excessive level of collisions.  Verifying the systems are running
half-duplex is also a very good idea.  Just keep in mind that Layer 1 issues
are not the only cause for network collisions.

A good example of this (Quick Search with TechNet) is 
http://support.microsoft.com/support/kb/articles/q169/7/89.asp

I appreciate the response and hope anyone with additional input steps
forward.

Thanks,
Ernie



-----Original Message-----
From: Peter Hicks [mailto:pwh at poggs.co.uk]
Sent: Monday, October 01, 2001 10:58 AM
To: Correale, Ernest
Cc: 'Steve Carter'; Samba List (E-mail); cc at poggs.co.uk
Subject: RE: Collisions


Ernest,

The underlying cause of Ethernet collisions is not the application, it is
the
physical network.

I agree, move to a switched environment at full duplex, but also check your
cables and that all clients on a hub are working at half duplex.


Peter.


On Mon, 1 Oct 2001, Correale, Ernest wrote:

> The collisions are probably caused by the client sending ACKs to confirm
> receipt of data.  Collisions are a normal part of Ethernet communication,
I
> wouldn't worry about it unless they are very severe.
>
> A solution would be to use a switch rather than a hub.  A switch will
allow
> two-way (Full-Duplex) communication between your server and client,
> eliminating the collision problem.
>
> Ernie
>
> -----Original Message-----
> From: Steve Carter [mailto:Steve.Carter at tradepartners.com]
> Sent: Monday, October 01, 2001 10:17 AM
> To: Samba List (E-mail)
> Subject: Collisions
>
>
> We're using samba across a 10MBit ethernet and seem to get collisions on
the
> hub when reading files, no matter how quiet the traffic.  I can only think
> that the smbd is beginning its reply before the request is fully finished.
> Anyone know whether this is the case and whther I can tune anything to
stop
> it happening?
>
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